Spectrex 20/20SH - Hydrogen Flame Detector - Manual (Page 45)

Spectrex Inc. - SharpEye TM Hydrogen (SH) Flame Detector Manual – TM 784600, Rev. A, May 2005
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Appendix A - Wire Selection Tables
General Instructions For Electrical Wiring
1. Refer to Table 12 to determine the required wire gauge for general wiring,
such as relay wiring. Calculate the permitted voltage fall with respect to
loads current, wire gauge and length of wires.
2. Refer to Table 13 to select wire gauge for power supply wires. DO NOT
connect any circuit or load to detectors’ supply inputs.
Table 12: Maximum DC resistance at 68˚F for copper wire
AWG # mm
2
Ohm per 100 ft. Ohm/100
meter
26 0.12 - 0.15 4.32 14.15
24 0.16 - 0.24 3.42 11.22
22 0.30 - 0.38 1.71 5.60
20 0.51 - 0.61 1.07 3.50
18 0.81 - 0.96 0.67 2.20
16 1.22 - 1.43 0.43 1.40
14 1.94 - 2.28 0.27 0.88
12 3.09 - 3.40 0.17 0.55
10 4.56 - 6.64 0.11 0.35
A. Select "Number of detectors" connected in one circuit.
B. Select "wiring length" per your installation requirements.
C. Refer to "power supply range" for voltage extreme applied.
Table 13. Wiring length in feet (meter)
No. of
Detectors Recommended Wire Diameter Power Supply
Range (VDC)
24 18 16 14 - - 22-32
20 18 16 14 - - 22-32
16 20 18 16 14 - 22-32
12 20 18 16 14 - 20-32
8 20 18 16 14 - 20-32
4 and less 20 18 16 16 14 20-32
Feet 164 328 492 656 820
(meters) (50) (100) (150) (200) (250)
Max. Length from Power Supply to Last
Detector